<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <title>盒子模型</title>
</head>

<body>
    <div class="outside-box">
        <div class="inside-box">
            <p>盒子模型</p>
        </div>
    </div>
</body>
<style>
    .outside-box {
        width: 300px;
        height: 200px;
        background-color: lightgreen;
        padding: 20px;
        border: 10px solid green;
        margin: 30px;
    }

    .inside-box {
        width: 200px;
        height: 100px;
        background-color: lightblue;
        padding: 20px;
        border: 10px solid greenyellow;
        margin: 30px;
    }
</style>

</html>